Present application relates to a method for realistic stitching and showing image blocks of an electronically recorded multipart image wherein relative positional offset values of the image blocks recorded with overlap are determined in a co-ordinate system in directions x and y and stored in matrix format, and the image blocks to be presented are stitched together on the basis of the stored values.
In the area of electronic image recording, one frequently encounters the need to show image parts that can be recorded/scanned in several parts only due to their size in a realistic manner and with adequate speed. By way of example, one such priority area is photography, the recording of panoramic images, virtual microscopy being another professional application area. In the latter field, several proposals have been released lately as to advantageous methods for stitching together individual image parts and expedient methods for showing these to the user or transmitting them in case of remote utilisation.
US 2006/0045388 A1 proposes several systems and methods for stitching image blocks, to create seamless magnified images of a microscope slide. In a microscopy system, several digital image block regions are defined for every actual, physical, slide, and the slide is scanned/electronically recorded by region; the recorded image parts are stored with a positional index metric associated to each image's location in a mosaic representation of the entire physical slide; a normalised correlation search is performed on the adjoining areas of next neighbour regional image blocks; a set of relative positional offset values and a correlation coefficient is determined for a regional image block and a next neighbour regional image block; a portion of the regional image blocks is viewed as a field of view of a display, and a composite of the portion of regional image blocks is stitched together in accord with a set of relative positional offset values and a correlation coefficient, such that only the blocks comprising the portion are stitched.
One drawback of this solution is that matching/stitching is applied exclusively to the image blocks being shown, at the moment of showing them. Normalised correlation search between 2-2 image blocks is unacceptably slow and does not yield optimum result, due to the confusing interference of larger-size, empty, but noisy, areas.
An object of the present invention is to develop a solution whereas the entire slide image can be stitched together from the image blocks in a short time, at low computing capacity demand and in excellent quality, given the demand for remote retrievals and related data transmission problems, cf. bandwidth.
We have realised that the efficiency of image stitching and transmission as well as the quality of the images themselves can be enhanced significantly by selecting small but very high-quality image blocks, and constructing the image of the slide around them and, furthermore, by performing the various operations not on the large-size image blocks themselves, but on their descriptors only.
According to a first aspect of the invention a method is proposed for the realistic stitching and showing of image blocks of an image recorded electronically, in several parts, whereas the relative positional offset values of the image blocks recorded with overlap are determined in a co-ordinate system, in directions x and y, and stored in matrix format, and the image blocks to be shown are stitched together on the basis of the stored values. According to the invention, the overlaps between the individual image blocks are subdivided into smaller regions; at least one region most useful for determining the stitching is identified; on the basis of the regions, a main offset direction vector is defined in correlation with the relative positional offset value; in addition to the relative positional offset value, an offset goodness value is defined as well; the blocks of the image are stitched together so that the two image block edges characterised by the best offset goodness values are stitched together first, and the two image block edges characterised by the worst offset goodness values are stitched together last, whereas, in the course of the stitching, only the image coordinates figuring in a matrix are modified; and any errors generated at the joins are distributed over several image blocks.
According to a second aspect of the invention a method is proposed for realistic stitching and showing image blocks of an electronically recorded multipart image whereas relative positional offset values of the image blocks recorded with overlap are determined in a coordinate system in directions x and y and stored in matrix format, and the image blocks to be shown are stitched together on the basis of the stored values. The method can, for example, include the steps of subdividing the overlaps of the individual image blocks into smaller regions with fixed relative positions; picking up at least one region most useful for the determination of the stitching; determining the offset goodness value based on the similarity of pattern of the image blocks; stitching the blocks of the image so that first the two image blocks characterised by the best offset goodness values are stitched together and the two image blocks characterised by the worst offset goodness values are stitched together last, with only the co-ordinates of the images figuring in a table being modified in the course of the stitching process; and distributing the errors produced by the stitching process over several image blocks.
Further advantageous embodiments of the invention are specified in the appended dependent claims.